US8956375B2 - Ultrasound catheter devices and methods - Google Patents

Abstract

Ultrasound catheter devices and methods provide enhanced disruption of blood vessel obstructions. Generally, ultrasound catheters include an elongate flexible catheter body with one or more lumens, an ultrasound transmission member extending longitudinally through the catheter body lumen and a distal head coupled with the transmission member and positioned adjacent the distal end of the catheter body for disrupting occlusions. Improved features of ultrasound catheters include prevention of independent rotation of the ultrasound transmission member, a safety anchor for the distal head, a one-piece transmission member/distal head and the like.

Description

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a divisional of U.S. patent application Ser. No. 11/493,430, filed Jul. 25, 2006, entitled “METHOD OF MANUFACTURING AN ULTRASOUND TRANSMISSION MEMBER FOR USE IN AN ULTRASOUND CATHETER,” which issued as U.S. Pat. No. 8,062,566, on Nov. 22, 2011, which is a divisional of U.S. patent application Ser. No. 10/410,617, filed Apr. 8, 2003, entitled “ULTRASOUND CATHETER DEVICES AND METHODS,” which issued as U.S. Pat. No. 7,220,233 on May 22, 2007, both of which are incorporated herein by reference. This application is also related to the following U.S. patent applications, the full disclosures of which are all hereby incorporated by reference: U.S. patent application Ser. No. 10/229,371, filed Aug. 26, 2002, entitled “ULTRASOUND CATHETER FOR DISRUPTING BLOOD VESSEL OBSTRUCTIONS,” which issued as U.S. Pat. No. 7,137,963, on Nov. 21, 2006; U.S. patent application Ser. No. 10/345,078, filed Jan. 14, 2003, entitled “ULTRASOUND CATHETER AND METHODS FOR MAKING AND USING SAME,” which issued as U.S. Pat. No. 7,604,608, on Oct. 20, 2009; and U.S. patent application Ser. No. 10/375,903, filed Feb. 26, 2003, entitled “ULTRASOUND CATHETER APPARATUS,” which issued as U.S. Pat. No. 6,942,677 on Sep. 13, 2005.

BACKGROUND OF THE INVENTION

The present invention relates generally to medical devices and methods. More specifically, the present invention relates to ultrasound catheter devices and methods for treating occlusive intravascular lesions.

Catheters employing various types of ultrasound transmitting members have been successfully used to ablate or otherwise disrupt obstructions in blood vessels. Specifically, ablation of atherosclerotic plaque or thromboembolic obstructions from peripheral blood vessels such as the femoral arteries has been particularly successful. Various ultrasonic catheter devices have been developed for use in ablating or otherwise removing obstructive material from blood vessels. For example, U.S. Pat. Nos. 5,267,954 and 5,380,274, issued to an inventor of the present invention and hereby incorporated by reference, describe ultrasound catheter devices for removing occlusions. Other examples of ultrasonic ablation devices for removing obstructions from blood vessels include those described in U.S. Pat. No. 3,433,226 (Boyd), U.S. Pat. No. 3,823,717 (Pohlman, et al.), U.S. Pat. No. 4,808,153 (Parisi), U.S. Pat. No. 4,936,281 (Stasz), U.S. Pat. No. 3,565,062 (Kuris), U.S. Pat. No. 4,924,863 (Sterzer), U.S. Pat. No. 4,870,953 (Don Michael, et al), and U.S. Pat. No. 4,920,954 (Alliger, et al.), as well as other patent publications WO87-05739 (Cooper), WO89-06515 (Bernstein, et al.), WO90-0130 (Sonic Needle Corp.), EP, EP316789 (Don Michael, et al.), DE3,821,836 (Schubert) and DE2438648 (Pohlman). While many ultrasound catheters have been developed, however, improvements are still being pursued.

Typically, an ultrasonic catheter system for ablating occlusive material includes three basic components: an ultrasound generator, an ultrasound transducer, and an ultrasound catheter. The generator converts line power into a high frequency current that is delivered to the transducer. The transducer contains piezoelectric crystals which, when excited by the high frequency current, expand and contract at high frequency. These small, high-frequency expansions and contractions have both longitudinal and transverse components (relative to an axis of the transducer and the catheter), which are amplified by the transducer horn into vibrational energy. The vibrations are then transmitted from the transducer through the ultrasound catheter via an ultrasound transmission member (or wire) running longitudinally through the catheter. The transmission member transmits the vibrational energy to the distal end of the catheter where the energy is used to ablate or otherwise disrupt a vascular obstruction.

To effectively reach various sites for treatment of intravascular occlusions, ultrasound catheters of the type described above typically have lengths of about 150 cm or longer. To permit the advancement of such ultrasound catheters through small and/or tortuous blood vessels such as the aortic arch, coronary vessels, and peripheral vasculature of the lower extremities, the catheters (and their respective ultrasound transmission wires) must typically be sufficiently small and flexible. Due to attenuation of ultrasound energy along the long, thin, ultrasound transmission wire, a sufficient amount of vibrational energy must be applied at the proximal end of the wire to provide a desired amount of energy at the distal end.

An ultrasound transmission wire is usually coupled at its proximal end with the transducer by means of a sonic connector. The sonic connector typically has a significantly larger diameter than that of the ultrasound transmission member, the difference in diameters helping to amplify the vibrational energy being transmitted from the transducer to the transmission wire. Several different means have typically been used for connecting the ultrasound transmission wire with the transducer via the sonic connector, such as complementary threads, pressure fitting and the like. One shortcoming of currently available devices is that they may allow the transmission wire to rotate independently from the catheter body. In these devices, it is not possible to rotate the ultrasound transmission wire by rotating, for example, a proximal handle or sonic connector assembly, since the transmission wire rotates freely and independently of the catheter body and such a proximal assembly.

Another potential drawback of currently available devices is that they often to not include optimal means for removing particles that are broken up or dislodged by the catheter. Yet another possible shortcoming is that many ultrasound catheter devices include a distal tip, as mentioned above, but do not have means for preventing the distal tip from migrating from the device into the patient's body if the tip breaks. Similarly, most ultrasound transmission members include multiple components for transmitting vibrational energy, which causes stresses at the connection points of the multiple components during use and potential breakage of the ultrasound transmission wire or other components. Also, ultrasound transmission wires are often exposed to increased amounts of stress due to one or more bends in patient vasculature, causing increased wear and tear on the transmission wire.

Therefore, a need exists for improved ultrasound catheter devices and methods that provide ablation or disruption of vascular occlusions. Ideally, such ultrasound catheters would include means for reducing or eliminating rotational motion of the ultrasound transmission wire relative to the catheter body. It would also be advantageous to have ultrasound catheters which included means for removing particles, preventing distal tip and ultrasound transmission wire migration, preventing stress at component connection points and/or preventing stress at bends in the catheter. Such catheter devices would ideally be sufficiently thin and flexible to be advanced through narrow, tortuous vasculature, such as the coronary vasculature, while also being configured to enhance the usable life of the ultrasound transmission wire. At least some of these objectives will be met by the present invention.

SUMMARY OF THE INVENTION

Ultrasound catheter devices and methods provide enhanced disruption of blood vessel obstructions. Generally, ultrasound catheters include an elongate flexible catheter body with one or more lumens, an ultrasound transmission member extending longitudinally through the catheter body lumen and a distal head coupled with the transmission member and positioned adjacent the distal end of the catheter body for disrupting occlusions. Improved features of ultrasound catheters include prevention of independent rotation of the ultrasound transmission member, a safety anchor for the distal head, a one-piece transmission member/distal head and the like.

In one aspect of the invention, an ultrasound catheter for disrupting occlusions in blood vessels comprises: an elongate flexible catheter body having a proximal end, a distal end and at least one lumen; an ultrasound transmission member extending longitudinally through the lumen of the catheter body and having a proximal end and a distal end; a distal head coupled with the distal end of the ultrasound transmission member and disposed adjacent the distal end of the catheter body; a sonic connector coupled with the proximal end of the ultrasound transmission member for coupling the ultrasound transmission member with an ultrasound transducer device; and a connector housing coupled with the proximal end of the catheter body for housing the sonic connector and a proximal portion of the ultrasound transmission wire and for preventing the ultrasound transmission member from rotating relative to the catheter body.

In some embodiments, the connector housing comprises a sonic connector cavity for holding the sonic connector to prevent it from rotating relative to the connector housing. Also in some embodiments, the ultrasound transducer device includes an ultrasound transducer housing having a proximal end and a distal end. In such embodiments, the connector housing may optionally be coupled with the distal end of the ultrasound transducer housing via coupling means allowing for manual coupling without using coupling tools. In one embodiment, the connector housing is coupled with the distal end of the ultrasound transducer housing via complementary threads on the two housings. Alternatively, the connector housing may be coupled with the distal end of the ultrasound transducer housing via pressure fitting. In some of these embodiments, the ultrasound transducer housing further comprises at least one protrusion on its distal end and a slidable collar for fitting over the at least one protrusion to press a portion of the distal end of the ultrasound transducer housing against the connector housing, thereby further securing the ultrasound transducer housing to the connector housing.

In another aspect, an ultrasound catheter for disrupting occlusions in blood vessels comprises: an elongate flexible catheter body having a proximal end, a distal end and at least one lumen; an ultrasound transmission member extending longitudinally through the lumen of the catheter body and having a proximal end and a distal end; a distal head coupled with the distal end of the ultrasound transmission member and disposed adjacent the distal end of the catheter body; a sonic connector coupled with the proximal end of the ultrasound transmission member for coupling the ultrasound transmission member with an ultrasound transducer device; and a rotation control member coupled with the proximal end of the catheter body for preventing the ultrasound transmission member from rotating relative to the catheter body. Optionally, the rotation control member may comprise a connector housing for housing the sonic connector and a proximal portion of the ultrasound transmission member. In some of such embodiments, the connector housing may comprise a sonic connector cavity for holding the sonic connector to prevent it from rotating relative to the connector housing. Also in some embodiments, the ultrasound transducer device includes an ultrasound transducer housing having a proximal end and a distal end. Again, the connector housing may be coupled, in some embodiments, with the distal end of the ultrasound transducer housing via coupling means allowing for manual coupling without using coupling tools. Such coupling may be by complementary threads on the two housings, pressure fitting or the like. In some embodiments, the ultrasound transducer housing further comprises at least one protrusion on its distal end and a slideable collar for fitting over the at least one protrusion to press a portion of the distal end of the ultrasound transducer housing against the connector housing, thereby further securing the ultrasound transducer housing to the connector housing.

In yet another aspect, an ultrasound catheter for disrupting occlusions in blood vessels comprises: an elongate flexible catheter body having a proximal end, a distal end and at least one lumen; an ultrasound transmission member extending longitudinally through the lumen of the catheter body and having a proximal end and a distal end; a distal head coupled with the distal end of the ultrasound transmission member and disposed adjacent the distal end of the catheter body; a sonic connector coupled with the proximal end of the ultrasound transmission member for coupling the ultrasound transmission member with an ultrasound transducer device; and means for coupling the sonic connector with the ultrasound transducer device while preventing the ultrasound transmission member from rotating relative to the catheter body. In some embodiments, the means for coupling comprises a housing for securing the sonic connector to prevent it from rotating relative to the housing.

In another aspect, an ultrasound catheter system for disrupting occlusions in blood vessels comprises: an elongate flexible catheter body having a proximal end, a distal end and at least one lumen; an ultrasound transmission member extending longitudinally through the lumen of the catheter body and having a proximal end and a distal end; a distal head coupled with the distal end of the ultrasound transmission member and disposed adjacent the distal end of the catheter body; a sonic connector coupled with the proximal end of the ultrasound transmission member; a connector housing having a proximal end and a distal end, the distal end coupled with the proximal end of the catheter body, for housing the sonic connector and a proximal portion of the ultrasound transmission wire and for preventing the ultrasound transmission member from rotating relative to the catheter body; and an ultrasound transducer device removably couplable with the sonic connector and the proximal end of the connector housing.

In some embodiments, the ultrasound transducer device includes an ultrasound transducer housing comprising at least one protrusion on a distal end of the ultrasound transducer housing and a slideable collar for fitting over the at least one protrusion to press a portion of the distal end of the ultrasound transducer housing against the connector housing, thereby further securing the ultrasound transducer housing to the connector housing. In some embodiments, the at least one protrusion comprises a first ring member at least partially encircling a portion of the ultrasound transducer housing. Sometimes the first ring member may include at least one longitudinal slot which narrows when the slideable collar is fitted over the first ring member to reduce an inner diameter of the first ring member. In some embodiments, the collar comprises a second ring member with an inner diameter to fit over at least part of the first ring member. In many embodiments, the slideable collar is slideable between an uncoupled position in which it does not contact the at least one protrusion and a coupled position in which it fits over the at least one protrusion. In some of these embodiments, the slideable collar does not overlap the connector housing when the collar is disposed in the coupled position or the uncoupled position.

In yet another aspect, an ultrasound catheter for disrupting occlusions in blood vessels comprises: an elongate flexible catheter body having a proximal end, a distal end and at least one lumen; an ultrasound transmission member extending longitudinally through the lumen of the catheter body and having a proximal end and a distal end; a distal head coupled with the distal end of the ultrasound transmission member and disposed adjacent the distal end of the catheter body; and at least one anchor member for anchoring the distal head to at least a part of the ultrasound catheter. In some embodiments, the at least one anchor member is coupled with the distal head and the catheter body. In some embodiments, the at least one anchor member is coupled with the catheter body closer to the distal end of the body than the proximal end of the body. Alternatively, the at least one anchor member may be coupled with the catheter body closer to the proximal end of the body than the distal end of the body. In other embodiments, the at least one anchor member is coupled with the distal head and a guidewire tube, the guidewire tube disposed within the catheter body and coupled with the catheter body. In yet other embodiments, the at least one anchor member comprises a guidewire tube disposed within the catheter body and coupled with the catheter body. In some embodiments, the at least one anchor member is coupled with at least one of the distal head and the catheter body by means selected from the group consisting of bonding, welding, fusing, tying and heat shrinking. In some embodiments, the at least one anchor member comprises at least one of a metal and a polymer.

In another aspect, an ultrasound catheter for disrupting occlusions in blood vessels, comprises: an elongate flexible catheter body having a proximal end, a distal end and at least one lumen; an ultrasound transmission member extending longitudinally through the lumen of the catheter body and having a proximal end, a distal end and a distal head, wherein the distal head and the rest of the ultrasound transmission member are manufactured from one piece of material; and a sonic connector coupled with the proximal end of the ultrasound transmission member for coupling the ultrasound transmission member with an ultrasound transducer device. In some embodiments, the ultrasound transmission member comprises at least one material having superelastic properties. Also in some embodiments, the distal head of the ultrasound transmission member comprises at least one longitudinal aperture. For example, the at least one longitudinal aperture may comprise at least one of an irrigation aperture and a guidewire aperture. In some embodiments, the ultrasound transmission member tapers from a larger diameter at its proximal end to a smaller diameter adjacent the distal head.

In another aspect, an ultrasound catheter for disrupting occlusions in blood vessels, includes: an elongate flexible catheter body having a proximal end, a distal end and at least one lumen; an ultrasound transmission member extending longitudinally through the lumen of the catheter body and having a proximal end and a distal end, the ultrasound transmission member comprising a metal alloy including at least two metal components and having a tensile strength of between 170,000 Psi and 250,000 Psi; and a distal head coupled with the distal end of the ultrasound transmission member and disposed adjacent the distal end of the catheter body, the distal head having an average density not to exceed 5 g/cm³. In some cases, the metal alloy comprises a superelastic alloy. For example, the superelastic alloy may be capable of elongation of between 7% and 17% in some embodiments. In one embodiment, the superelastic alloy comprises a nickel-titanium alloy having a nickel content of between 50.50 and 51.50 atomic weight. Optionally, the superelastic alloy may have a superelastic temperature range of between 10° C. and 50° C.

In still another aspect, an ultrasound catheter for disrupting occlusions in-blood vessels includes: an elongate flexible catheter body having a proximal end, a distal end and at least one lumen, the catheter body comprising at least in part a polymeric material having a flexural modulus of elasticity of less than 160 Psi; an ultrasound transmission member extending longitudinally through the lumen of the catheter body and having a proximal end and a distal end; a distal head coupled with the distal end of the ultrasound transmission member and disposed adjacent the distal end of the catheter body; and a sonic connector coupled with the proximal end of the ultrasound transmission member for coupling the ultrasound transmission member with an ultrasound transducer device. In some embodiments, the polymeric material comprises a polymeric block amide. In some embodiments, the polymeric block amide has a Shore D hardness value of between about 55 and about 75. Alternatively, the polymeric block amide may have a Shore D hardness value of between about 25 and about 55. Also in some embodiments, 5% or less of the polymeric material may comprise a colorant.

In another aspect of the invention, a method of manufacturing an ultrasound transmission member for use in an ultrasound catheter device involves: providing a generally cylindrically-shaped transmission member material; shaping the material to taper the transmission member from a first, wider end toward a second, narrower end; and forming a distal head at the second, narrower end. In some cases, providing the material comprises providing a polymer having superelastic properties. Shaping the material, in some embodiments, comprises grinding the material. Forming the distal head, in some embodiments, comprises forming a bullet-shaped head. Optionally, forming the distal head may further comprise forming at least one longitudinal aperture through the head to provide for passage of at least one of a guidewire and irrigation fluid.

In another aspect, a method for disrupting an occlusion in a blood vessel includes: positioning an ultrasound catheter in the blood vessel such that a distal end of the catheter is adjacent the occlusion; transmitting ultrasound energy to an ultrasound transmission member of the ultrasound catheter to disrupt the occlusion into multiple occlusion fragments; expanding an expandable balloon coupled with the ultrasound catheter at a location proximal to the distal end of the catheter; and removing at least some of the occlusion fragments from the blood vessel via the ultrasound catheter. In some embodiments, positioning the ultrasound catheter comprises guiding the catheter using a guidewire. Optionally, the occlusion fragments may be removed through at least one aperture in a catheter body of the ultrasound catheter. In some embodiments, for example, the at least one aperture is in fluid communication with at least one irrigation lumen and the occlusion fragments are removed through the at least one aperture and the at least one irrigation lumen. Alternatively, the at least one aperture may be in fluid communication with at least one guidewire lumen and the occlusion fragments are removed through the at least one aperture and the at least one guidewire lumen. In another embodiment, the occlusion fragments are removed through a sheath disposed around a portion of the ultrasound catheter. In any such embodiments, removing the occlusion fragments may comprise applying a vacuum force to guide the fragments into at least one aperture on the ultrasound catheter. For example, applying the vacuum may comprise using at least one of a syringe and a vacuum pump.

In another aspect of the invention, a method for disrupting an occlusion in a blood vessel comprises: introducing an ultrasound catheter into the blood vessel through a guide catheter; positioning the ultrasound catheter such that a distal end of the catheter is adjacent the occlusion; transmitting ultrasound energy to an ultrasound transmission member of the ultrasound catheter to disrupt the occlusion into multiple occlusion fragments; expanding an expandable balloon coupled with the guide catheter at a location proximal to the distal end of the catheter; and removing at least some of the occlusion fragments from the blood vessel via the ultrasound catheter. Optionally, introducing and positioning the ultrasound catheter may further comprise guiding the catheter using a guidewire.

In yet another aspect, a method for disrupting an occlusion in a blood vessel involves: positioning an ultrasound catheter in the blood vessel such that a distal end of the catheter is adjacent the occlusion; introducing at least one radiopaque fluid into the blood vessel through at least one aperture in the ultrasound catheter adjacent the distal end to enhance visualization of a location of the distal end; and transmitting ultrasound energy to an ultrasound transmission member of the ultrasound catheter to disrupt the occlusion into multiple occlusion fragments. Optionally, introducing the radiopaque fluid may comprise introducing through at least one irrigation aperture in the ultrasound catheter. Alternatively, introducing the radiopaque fluid may comprise introducing through at least one guidewire aperture in the ultrasound catheter. In yet other embodiments, introducing the radiopaque fluid comprises introducing through a sheath surrounding a portion of the ultrasound catheter and forming the at least one aperture.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a perspective view of a system including an ultrasound catheter device and ultrasound energy source according to an embodiment of the present invention;

FIG. 2 is a perspective view of a proximal housing, sonic connector and ultrasound transmission member of an ultrasound catheter device according to an embodiment of the present invention;

FIG. 3 is a cross-sectional side view of an ultrasound catheter device according to an embodiment of the present invention;

FIGS. 4A and 4B are cross-sectional side views of a proximal portion of an ultrasound catheter device coupled with a distal end of an ultrasound transducer device, showing a collar in unengaged (FIG. 4A) and engaged (FIG. 4B) positions according to an embodiment of the present invention;

FIGS. 5A and 5B are perspective views of an ultrasound catheter device coupled with a distal end of an ultrasound transducer device, showing a collar in unengaged (FIG. 5A) and engaged (FIG. 5B) positions according to an embodiment of the present invention;

FIG. 6 is a side view of an ultrasound catheter device with a balloon and apertures for irrigation and suction according to an embodiment of the present invention;

FIG. 7 is a side view of an ultrasound catheter device with a balloon and apertures for irrigation and suction according to another embodiment of the present invention;

FIG. 8 is a side view of an ultrasound catheter device with a balloon and apertures for irrigation and suction according to still another embodiment of the present invention;

FIG. 9 is a cross-sectional side view of a distal end of an ultrasound catheter device with an anchor member according to an embodiment of the present invention;

FIG. 10 is a cross-sectional side view of a distal end of an ultrasound catheter device with an anchor member according to another embodiment of the present invention;

FIG. 11 is a cross-sectional side view of a distal end of an ultrasound catheter device with an anchor member according to still another embodiment of the present invention; and

FIGS. 12A-12C illustrate a method of manufacturing an ultrasound transmission member for use in an ultrasound catheter device according to an embodiment of the present invention.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT

Ultrasound catheter devices and methods of the present invention may generally be used for treating occlusions in blood vessels. Catheter devices generally include a catheter body, an ultrasound energy transmission member disposed within the catheter body and a distal head coupled with the energy transmission member and disposed at or near the distal end of the catheter body. The ultrasound transmission member transmits ultrasound energy from an ultrasound transducer to the distal head, causing the head to vibrate and, thus, disrupt vascular occlusions. A number of improved features of such ultrasound catheter devices are described more fully below.

Referring now toFIG. 1, one embodiment of anultrasound catheter system20 suitably includes anultrasound catheter device10, including aproximal end connector12 forcoupling device10 with anultrasound transducer14, and anultrasound generator16 coupled withtransducer14 and a foot-actuated on/offswitch18 to provide ultrasonic energy totransducer14 and, thus, toultrasound catheter10. Generally,catheter10 includes an ultrasound transmission member, or wire (not shown), for transmitting energy from thetransducer14 to adistal head26 ofcatheter10. In some embodiments,transducer14 further includes a securingdevice15 for enhancing coupling ofcatheter10 totransducer14. Components ofsystem20 may be coupled via any suitable means, such as connecting wires of any kind, wireless connections or the like.

In addition toproximal connector12,ultrasound catheter device10 may include one or more other various components, such as a Y-connector11 or the like for providing access for irrigation, guidewire passage, suction or the like. Some embodiments of device include arapid exchange guidewire13, some include aproximal guidewire port17 for over the wire guidewire deliver, and some embodiments include both. In some embodiments, Y-connector may include an irrigation port, for providing access for anirrigation tube24.Irrigation tube24, in some embodiments, may be used for introducing one or more fluids, applying vacuum, or both. Generally,catheter device10 may include any suitable number of side-arms or ports for passage of a guidewire, infusing and/or withdrawing irrigation fluid, dye and/or the like, or any other suitable ports or connections. Also,ultrasound catheters10 of the present invention may be used with any suitable proximal devices, such as anysuitable ultrasound transducer14,ultrasound generator16, coupling device(s) and/or the like. Therefore, exemplaryFIG. 1 and any following descriptions of proximal apparatus or systems for use withultrasound catheters10 should not be interpreted to limit the scope of the present invention as defined in the appended claims.

Referring now toFIG. 3, a cross-sectional side view of one embodiment ofultrasound catheter device10 is shown. Generally,ultrasound catheter10 suitably includes anelongate catheter body22 with anultrasound transmission member24 disposed longitudinally through acatheter lumen21 and ending in distal head (not shown).Catheter body22 is generally a flexible, tubular, elongate member, having any suitable diameter and length for reaching a vascular occlusion for treatment. In one embodiment, for example,catheter body22 preferably has an outer diameter of between about 0.5 mm and about 5.0 mm. In other embodiments, as in catheters intended for use in relatively small vessels,catheter body22 may have an outer diameter of between about 0.25 mm and about 2.5 mm.Catheter body22 may also have any suitable length. As discussed briefly above, for example, some ultrasound catheters have a length in the range of about 150 cm. However, any other suitable length may be used without departing from the scope of the present invention. Examples of catheter bodies similar to those which may be used in the present invention are described in U.S. Pat. Nos. 5,267,954 and 5,989,208, which were previously incorporated herein by reference.

In some embodiments,catheter body22 is made from a polymeric material. Sometimes the polymer will have a desired amount of flexibility, such as in one embodiment wherecatheter body22 is made of a polymer having a flexural modulus of less than about 160 Psi. In some embodiments, such a polymer will be one of any number of polyether block amides, although other polymers may of course be used. In some embodiments, such polyether block amides may have a Shore D hardness value ranging from about 55 to about 75, while in other embodiments they may have a Shore D hardness value ranging from about 25 to about 55. In some embodiments, the polymeric material includes up to about 5 weight percent of a colorant.

In most embodiments,ultrasound transmission member24, wire, or wave guide extends longitudinally throughcatheter body lumen21 to transmit ultrasonic energy fromultrasound transducer14, connected to the proximal end ofcatheter10, to the distal end ofcatheter10.Ultrasound transmission member24 may be formed of any material capable of effectively transmitting ultrasonic energy fromultrasound transducer14 to the distal end ofcatheter body22, including but not limited to metals such as pure titanium or aluminum, or titanium or aluminum alloys.

With continued reference toFIG. 3, one embodiment ofproximal end connector12 suitably includes ahousing42 with a hollowinner bore44.Bore44 may have a uniform inner diameter along its length or, alternatively, may have multiple segments, such as aproximal segment47, amiddle segment45 and adistal segment49, each of which may surround one or more various components ofproximal end connector12. Generally,proximal segment47 ofbore44 is configured to allow coupling with ultrasound transducer14 (not shown) via any suitable coupling means, such as a pressure fit, complementary threads or the like.Proximal segment47 includes asonic connector52 for transmitting vibrational energy fromtransducer14 toultrasound transmission member24.Sonic connector52 may be held withinhousing42 by any suitable means. In some embodiments, for example, a dowel pin may extend throughsonic connector52 to hold it withinhousing42.

In another embodiment, and with reference now toFIG. 2,sonic connector52 may be secured withinhousing42 by means of acavity202 inhousing42.Cavity202, in some embodiments, will have a complementary shape tosonic connector52, such thatsonic connector52 fits snugly withincavity202 to prevent rotation ofsonic connector52 independent ofhousing42. InFIG. 2, for example,sonic connector52 hasflat sides204 which correspond with the shape ofcavity202. Any other suitable shape/configuration is contemplated. By preventing free rotation ofsonic connector52,housing42 andcavity202 also prevent free rotation ofultrasound transmission member24, which is securely coupled withsonic connector52. Conversely, if rotation ofultrasound transmission member24 is desired, a user ofdevice10 can rotatehousing42, such as by rotating it in his/her hand, and this rotation ofhousing42 will be transmitted tosonic connector52 andultrasound transmission member24.

Returning toFIG. 3,middle segment45 ofbore44, in some embodiments, may surround a portion ofsonic connector52, while in other embodiments,sonic connector52 may be housed only withinproximal segment47.Sonic connector52 is coupled with the proximal end ofultrasound transmission member24 by any suitable means for transmitting ultrasound energy totransmission member24 fromtransducer14.Absorber members50, such as O-rings, surround a portion ofultrasound transmission member24 for providing absorption of transverse vibration.Absorber members50 may be used in any number or combination and have and suitable size and configuration, depending on the desired level of vibration absorption or dampening. Alternatively or additionally, other dampening structures may be used. Thus, the invention is not limited to the combination shown inFIG. 3.

Distal segment49 ofbore44 typically surrounds a portion ofultrasound transmission member24 and may also contain one or more additional sets ofabsorber members50.Distal segment49 may also contain a portion of a Y-connector11, which is coupled with the distal end ofhousing42. Coupling of Y-connector11 with the distal end ofhousing42 may be accomplished via complementary threads, pressure fitting, or any other suitable means. A Y-connector lumen48 of Y-connector11 allows passage ofultrasound transmission member24 and is in fluid communication withcatheter body lumen21.

Generally, pressurized fluid such as a coolant liquid may be infused through a side-arm13 of Y-connector, through Y-connector lumen48 and throughcatheter body lumen21 so that it flows out of one or more fluid outflow apertures indistal head26. The temperature and flow rate of such coolant liquid may be specifically controlled to maintain the temperature ofultrasound transmission member24 at a desired temperature within its optimal working range. In particular, in embodiments of the invention whereinultrasound transmission member24 is formed of a metal alloy which exhibits optimal physical properties (e.g. super elasticity) within a specific range of temperatures, the temperature and flow rate of coolant liquid infused through fluid infusion side-arm13 may be specifically controlled to maintain the temperature ofultrasound transmission member24 within a range of temperatures at which it demonstrates its most desirable physical properties. For example, in embodiments of the invention whereinultrasound transmission member24 is formed of a shape memory alloy which exhibits super elasticity when in its martensite state, but which loses super elasticity as it transitions to an austenite state, it will be desirable to adjust the temperature and flow rate of the coolant liquid infused through fluid infusion side-arm13 so as to maintain the shape memory alloy ofultrasound transmission member24 within a temperature range at which the alloy will remain in its martensite state and will not transition to an austenite state. The temperature at which such shape memory alloys transition from a martensite state to an austenite state is known as the “martensite transition temperature” of the material. Thus, in these embodiments, the fluid infused through side-arm13 will be at such temperature, and will be infused at such rate, as to maintain the shape memory alloy ofultrasound transmission member24 below its martensite transition temperature.

Referring now toFIGS. 4A and 4B cross-sectional side views of one embodiment of the coupling ofproximal connector12 with the distal end of atransducer device400. Generally, transducer device will include atransducer housing402,piezoelectric crystals404, atransducer horn406, and any suitable coupling means412 forcoupling transducer horn406 withsonic connector52. Coupling means412 may include, for example, complementary threads, a pressure fitting configuration or the like. In some embodiments,transducer housing402 includes aslidable collar408 and at least onesurface protrusion410.Surface protrusion410 generally fits over the outer surface ofhousing42 ofproximal connector12. In some embodiments, as shown inFIGS. 4A and 4B,protrusion410 may be a ring surrounding a portion oftransducer housing402, though any other configuration is contemplated.Slidable collar408, in turn, is slidable between an unengaged position, as inFIG. 4A, and an engaged position, as inFIG. 4B. In the engaged position,slidable collar408 fits around the outer diameter ofprotrusion410 sufficiently tightly to apply pressure againstprotrusion410. This pressure pressesprotrusion410 againsthousing42 to further securetransducer housing402 toproximal connector12. This further securing prevents unwanted separation ofultrasound catheter device10 fromtransducer device400. Any other suitable configurations, shapes, sizes and the like ofcollar408 andprotrusion410 are contemplated.

With reference now toFIGS. 5A and 5B,ultrasound catheter device10 is shown coupled withtransducer housing402.FIG. 5A showsslidable collar408 in its unengaged position, whileFIG. 5B showscollar408 in its engaged position. In some embodiments,protrusion410 may be a ring making up or surrounding a portion oftransducer housing402, as mentioned above. Also in some embodiments,protrusion410, such as a ring, may include aslot414 or other opening, which may go through all or part of the thickness ofprotrusion410. Slot414 generally allowsprotrusion410 to give or bend whencollar408 is fitted overprotrusion410, thus reducing the inner diameter ofprotrusion410 to press against the outer surface ofproximal connector device12. Again, any suitable configuration forslot414 is contemplated within the scope of the present invention. Whencollar408 is engaged, as shown inFIG. 5B,transducer housing402 orproximal connector12 may be rotated, and ultrasound catheter device10 (with ultrasound transmission member24) will rotate in turn. Such rotation may be accomplished even whencollar408 is in the unengaged position (FIG. 5A), butcollar408 andprotrusion410 enhance coupling oftransducer housing402 andproximal connector12, to provide additional control and to assure thattransducer housing402,proximal connector12 and the rest ofultrasound catheter device10 either rotate together or do not rotate.

Referring now toFIGS. 6-8, various embodiments of a distal end ofultrasound catheter device10 are shown within ablood vessel430, adjacent anocclusion432. Various embodiments ofultrasound catheter device10 include one or moreexpandable members422, such as balloons, as well as one or morefluid apertures426 indistal head26. Some embodiments may also include, or may be used in conjunction with, aguide catheter420 having aguide catheter aperture421. In one embodiment, as shown inFIG. 6, fluid may be introducedadjacent occlusion432 viafluid apertures426 and/or guidecatheter aperture421. Oncecatheter device10 has begun to breakocclusion432 intomultiple fragments428, fluid (either by itself or containing the fragments) may be removed fromblood vessel430 viafluid apertures426 and/or guidecatheter aperture421. InFIG. 6, fluid is being introduced via guide catheter aperture421 (arrows), and fluid andfragments428 are being removed viafluid apertures426. The opposite may also be possible. Such fluid introduction and fluid/fragment removal are enhanced in some embodiments by expanding aballoon422 proximal to the fluid introduction/removal apertures. In the embodiment shown inFIG. 6,balloon422 is coupled withguide catheter420.

With reference toFIG. 7, in an alternative embodiment,balloon422 is coupled withcatheter body22 rather than guidecatheter420. In this embodiment, fluid may be introduced by one or morefluid apertures427 and fluid andfragments428 may be removed via one or more otherfluid apertures426. Generally, any suitable combination offluid apertures426,427 for infusion of fluids and/or aspiration of fluids and/or particles may be used. In yet another embodiment, and with reference now toFIG. 8,ultrasound catheter device10 may include asheath424 around its outer circumference, the sheath forming asheath aperture425.Sheath aperture425 may then be used for fluid introduction and/or removal of fluid/fragments428. InFIG. 8, for example, fluid is shown exitingfluid apertures426 and entering sheath aperture425 (arrows). Virtually any suitable combination of apertures and expandable members is contemplated by the present invention. The use of apertures and expandable members generally enhances operation of ultrasound catheter device in breaking down occlusions and removing occlusion fragments harmlessly from the patient.

With reference now toFIGS. 9-11, various embodiments of the distal end ofultrasound catheter device10 are shown in cross-sectional side view suitably includes anelongate catheter body22 with at least one hollowcatheter body lumen21. InFIGS. 9-11,catheter body22 is shown having onelumen21, but it may have any number of lumens in various embodiments. Disposed longitudinally withincatheter body lumen21 are anultrasound transmission member24 and ahollow guidewire tube28 forming aguidewire lumen29. Coupled with the distal ends ofultrasound transmission member24 andguidewire tube28 is adistal head26, positioned adjacent the distal end ofcatheter body22.

Generally, the various coupled components described above may be coupled by any suitable means, such as adhesives, complementary threaded members, pressure fittings, and the like. For example,distal head26 may be coupled withultrasound transmission member24 andguidewire tube28 with any suitable adhesive substance or via welding, bonding or the like. Adhesives used to attachguide wire tube28,distal head26 and/orcatheter body22 may include, but are not limited to cyanoacrylate (eg. Loctite™, Loctite Corp., Ontario, CANADA or Dron Alpha™, Borden, Inc., Columbus, Ohio) or polyurethane (e.g. Dymax™, Dymax Engineering Adhesive, Torrington, Conn.) adhesives. In some embodiments,guidewire tube28 may also be coupled withcatheter body22 by adhesive, welding or other means. Some embodiments may also include one or more anchoring members for further securingdistal head26 to theultrasound catheter device10 and to help ensure thatdistal head26 does not break free ofcatheter device10.

For example, referring toFIG. 9, in one embodiment an anchoringmember440 may be connected at one end todistal head26 and at the other end tocatheter body22. Again, any connection means may be used, such as but not limited to adhesives, welding, bonding and/or the like. Furthermore, anchoringmember440 may be connected todistal head26 andcatheter body22 at any suitable locations. Another embodiment is shown inFIG. 10, in which anchoringmember440 is coupled withdistal head26 andguidewire tube28. This connection may provide similar safety and prevention ofdistal head26 migration. Finally, in some embodiments, as shown inFIG. 11,guidewire tube28 itself acts as an anchor, and a separate anchoring member is not used. Any suitable configuration and combination is contemplated by the scope of the present invention.

Finally, and with reference now toFIGS. 12A-12C, one embodiment of anultrasound transmission member24 and a method for making same is shown. In this embodiment,ultrasound transmission member24 is made from a unitary piece ofprecursor material450 and includesdistal head26. Thus there is no separate distal head piece that is attached toultrasound transmission member24—instead it is all one piece. Generally,ultrasound transmission member24 may be formed of any material450 capable of effectively transmitting ultrasonic energy fromultrasound transducer14 to the distal end ofcatheter body22, including but not limited to metals such as titanium and nickel alloys.

In accordance with one aspect of the invention, all or a portion ofultrasound transmission member24 may be formed of one ormore materials450 which exhibit superelastic properties. Such material(s)450 should preferably exhibit superelasticity consistently within the range of temperatures normally encountered byultrasound transmission member24 during operation ofultrasound catheter apparatus10. For example, in some embodiments,material450 is an alloy having a tensile strength of between about 170,000 Psi and about 250,000 Psi. In some embodiments, the alloy exhibits elongation of between about 7% and about 17%. For example, in some embodiments the alloy is a nickel-titanium alloy having nickel content of between about 50.50 and about 51.50 atomic weight.

Use of superelastic metal alloys in ultrasound transmission members is described in U.S. Pat. No. 5,267,954, previously incorporated by reference. Examples of superelastic metal alloys which may be used are described in detail in U.S. Pat. No. 4,665,906 (Jervis); U.S. Pat. No. 4,565,589 (Harrison); U.S. Pat. No. 4,505,767 (Quin); and U.S. Pat. No. 4,337,090 (Harrison), the entire disclosures of which are hereby incorporated by reference insofar as they describe the compositions, properties, chemistries and behavior of specific metal alloys which are superelastic within the temperature range at whichultrasound transmission member24 of the present invention operates, any and all of which superelastic metal alloys may be used to formultrasound transmission member24 of the present invention. In some embodiments, for example, the alloy exhibits a superelastic temperature range of about 10 degrees Celsius to about 50 degrees Celsius.

In many embodiments,ultrasound transmission member24 includes awider region452 toward its proximal end and one or moretapered regions454 towards its distal end.Tapered region454 decreases the distal rigidity ofultrasound transmission member24, thus amplifying ultrasound energy transmitted alongultrasound transmission member24 todistal head26.Distal head26 may have any suitable configuration, shape, and size suitable for ablating or otherwise disrupting occlusions. For example,distal head26 may have a shape that is bulbous, conical, cylindrical, circular, rectangular or the like. Similarly,distal head26 may have dimensions which allow it to fit wholly or partially within the distal end ofcatheter body lumen21 or may, alternatively, be disposed completely outsidecatheter body lumen21. Thus, the configuration ofdistal head26 may take any suitable form and should in no way be limited by the exemplary embodiments pictured inFIGS. 12A-12C.

In one embodiment, a method of makingultrasound transmission member24 involves providing transmission member precursor material450 (FIG. 12A), removing some ofmaterial450 by any suitable process to formtransmission member24 and distal head26 (FIG. 12B), and then removing additional material from distal head to form one or more fluid apertures426 (FIG. 12C). Removing material to form transmission member may be performed via any suitable method, such as sanding, grinding, cutting or the like. Similarly, removing material to formapertures426 may be performed via any suitable method, such as boring throughdistal head26. Any analogous methods are contemplated within the scope of the invention.

Although the invention has been described above with specific reference to various embodiments and examples, it should be understood that various additions, modifications, deletions and alterations may be made to such embodiments without departing from the spirit or scope of the invention. Accordingly, it is intended that all reasonably foreseeable additions, deletions, alterations and modifications be included within the scope of the invention as defined in the following claims.

Claims (20)

What is claimed is:

1. A method comprising:

providing a catheter with

a body comprising one or more distal apertures, an outer diameter, and a distal portion;

one or more lumens situated substantially longitudinally through the body;

a member partially disposed within one of the lumens that continuously tapers through a region from a wider end to a distal head at a narrower end, wherein the distal head has a proximal end disposed within the distal portion, wherein the proximal end has a diameter smaller than the diameter of the distal portion, wherein the distal head has a distal end disposed distally to the distal portion, and wherein the distal end has a diameter approximately equal to the outer diameter of the body; and

a guide catheter disposed over the body, the guide catheter having a lumen;

a sheath disposed over the body and within the guide catheter lumen, the sheath having a lumen;

a balloon disposed on the guide catheter;

positioning the distal head adjacent a blood vessel occlusion;

transmitting ultrasound energy through the member to fragment the occlusion;

introducing fluid into the blood vessel through the one or more distal apertures and the guide catheter lumen;

expanding the balloon;

and

removing fragments through the sheath lumen.

2. The method ofclaim 1 in which

the catheter further comprises a guidewire extending through one of the lumens

and

positioning the distal head comprises guiding the catheter using the guidewire.

3. The method ofclaim 1 in which removing fragments uses at least one distal aperture.

4. The method ofclaim 3 in which at least one distal aperture forms a conduit with the guidewire lumen and removing fragments uses the conduit.

5. The method ofclaim 1 in which at least one distal aperture forms a conduit with an irrigation lumen located in the body and removing fragments uses the conduit.

6. The method ofclaim 1 in which removing fragments comprises evacuating a fragment through an aperture.

7. The method ofclaim 6 in which evacuating uses a syringe, a pump, or both.

8. The method ofclaim 1 further comprising introducing a fluid through the catheter.

9. The method ofclaim 8 wherein fluid comprises a radiopaque material to improve visualization of the distal end.

10. A method comprising:

providing a catheter with

a body comprising one or more distal apertures, and a distal portion;

one or more lumens situated substantially longitudinally through the body;

a member partially disposed within one of the lumens that continuously tapers through a region from a wider end to a distal head at a narrower end, wherein the distal head has a proximal end disposed within the distal portion, wherein the proximal end has a diameter smaller than the diameter of the distal portion, wherein the distal head has a distal end disposed distally to the distal portion, and wherein the distal end has a diameter approximately equal to the outer diameter of the body; and

a guide catheter disposed over the body, the guide catheter having a lumen;

a sheath disposed over the body and within the guide catheter lumen, the sheath having a lumen;

a balloon disposed on the guide catheter;

positioning the distal head adjacent a blood vessel occlusion;

transmitting ultrasound energy through the member to fragment the occlusion;

expanding the balloon;

introducing a fluid into a region distal to the balloon;

introducing a second fluid into the blood vessel through the one or more distal apertures and the guide catheter lumen;

and

removing fragments through the sheath lumen.

11. The method ofclaim 10 in which

the catheter further comprises a guidewire extending through one of the lumens

and

positioning the distal head comprises guiding the catheter using the guidewire.

12. The method ofclaim 11 in which removing fragments uses at least one distal aperture.

13. The method ofclaim 12 in which at least one distal aperture forms a conduit with the guidewire lumen and removing fragments uses the conduit.

14. The method ofclaim 13 in which at least one distal aperture forms a conduit with an irrigation lumen located in the body and removing fragments uses the conduit.

15. The method ofclaim 14 wherein the fluid comprises a radiopaque material to improve visualization of the distal end.

16. A method comprising:

providing a catheter with

a body comprising one or more distal apertures, and a distal portion;

one or more lumens situated substantially longitudinally through the body;

a member partially disposed within one of the lumens that continuously tapers through a region from a wider end to a distal head at a narrower end, wherein the distal head has a proximal end disposed within the distal portion, wherein the proximal end has a diameter smaller than the diameter of the distal portion, wherein the distal head has a distal end disposed distally to the distal portion, and wherein the distal end has a diameter approximately equal to the outer diameter of the body; and

a guide catheter disposed over the body, the guide catheter having a lumen;

a sheath disposed over the body and within the guide catheter lumen, the sheath having a lumen;

a balloon disposed on the guide catheter;

positioning the distal head adjacent a blood vessel occlusion;

transmitting ultrasound energy through the member to fragment the occlusion;

introducing at least one radiopaque fluid into the blood vessel through at least one distal aperture to improve visualization of the distal end;

introducing a second fluid into the blood vessel through the one or more distal apertures and the guide catheter lumen;

and

removing fragments through the sheath lumen.

17. The method ofclaim 16 in which at least one distal aperture forms a conduit with an irrigation lumen located in the body and removing fragments uses the conduit.

18. The method ofclaim 16 further comprising expanding the balloon, wherein introducing occurs at a region distal to the balloon.

19. The method ofclaim 16 in which positioning the catheter comprises introducing the catheter through the guide catheter.

20. The method ofclaim 19 in which at least one distal aperture forms a conduit with an irrigation lumen located in the body and removing fragments uses the conduit.

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